1. Field of the Invention
The present invention relates to apparatus for transporting cargo, and in particular, to a device having a cargo support that can be articulated before unloading the cargo.
2. Description of Related Art
People often wish to transport equipment such as motorcycles or personal water craft with small trucks such as pickup trucks. A serious difficulty is lifting such equipment onto the truck bed. U.S. Pat. No. 5,249,910 proposes using a winch to load and unload cargo over a ramp. A ramp may be inappropriate for unloading equipment such as a personal water craft onto land. First, significant effort is required to push the craft horizontally across the truck bed and onto the ramp. Once on the ramp, one end of the craft can be brought to the ground, but must then be lifted and pulled out to allow the rest of the craft to descend the ramp. Alternatively, the truck can be moved forward as the craft completes its descent on the ramp, but this procedure is complicated and will normally require two operators. Also, loading can be difficult because the craft must pass the crest of the ramp and rapidly change its angle of elevation, before becoming horizontal on the truck bed. The rocking occurring at this transition also means that the full weight of the craft is supported essentially at a single point, which runs the risk of applying excessive pressure and damaging the hull.
Commercially available trucks for hauling vehicles include a platform that tilts before being slid backwardly to reach the ground and form a ramp. The cargo must still make the transition from the ground onto the ramp, which is not difficult with wheeled vehicles, but can be difficult with other cargo such as water craft. More importantly, this technology requires that the truck be dedicated to hauling vehicles and is therefore impractical for users who may wish to use their truck other purposes. U.S. Pat. No. 5,511,928 shows a boat hauling accessory that can be placed on an ordinary pickup truck, but has a platform that always stays tilted, so that the forward end remains high over the truck cab while traveling. Also, this arrangement does not solve the problem of moving the cargo from the ground to the platform. See U.S. Pat. No. 5,846,047 for a tilting platform that does not slide longitudinally.
In U.S. Pat. No. 5,603,600 a ramp is formed of two telescoping sections. Cargo can be loaded on one section of the ramp, which then slides upon the other section to lift the cargo up over the truck bed. The collapsed ramp then pivots into a horizontal position. This device does not solve the problem of lifting the cargo onto or off the ramp. Also, this device keeps the cargo high off the truck bed, apparently to accommodate the mechanism that rotates the ramp. Such a configuration, however, raises the center of gravity, and reduces the stability of the truck and its cargo.
In U.S. Pat. No. 5,380,141 a similar arrangement is shown where the first section deployed does not support the cargo, but is positioned behind the truck and supported by a separate vertical support member. Thereafter, the section carrying the cargo is slid over the already deployed member, and then both members can be tilted to form a ramp. This arrangement has the same difficulty with loading/unloading the cargo from/to the ground and also keeps the cargo high and therefore degrades stability.
In U.S. Pat. No. 5,232,329 one end of a detachable platform can be lifted by a cable suspended over a boom whose angle of elevation is controlled by a hydraulic cylinder. The boom is then swung from an obtuse angle to an acute angle to allow the detachable platform to ride up the boom. Swinging the boom through such a large angle requires a relatively long hydraulic cylinder, and for this reason, the boom and cargo remains high off the truck bed after loading. See also U.S. Pat. No. 5,620,296 for another boom arrangement.
Accordingly, there is in need for a cargo carrier that can be mounted on a vehicle bed and which simplifies the process of loading and unloading cargo.
In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a carrier adapted for mounting in a vehicle bed for carrying cargo. The carrier has a stationary support mounted on the vehicle bed. Also included is an articulated support and a cargo support. The articulated support has a proximal end pivotally mounted on the stationary support. The carrier also has an elevation means for articulating the articulated support. The cargo support is mounted for longitudinal motion on the articulated support. The cargo support is operable to detach and reattach to the articulated support at a handoff location located at the proximal end of the articulated support. The carrier also has a motive means for moving the cargo support. This motive means includes a guide means located at the handoff location for vertically translating and supporting an end of the cargo support from the handoff location.
In accordance with another aspect of the invention there is provided, a carrier adapted for mounting in a vehicle bed for carrying cargo. The carrier has a stationary support and an articulated support. The stationary support is mounted on the vehicle bed. The articulated support has a proximal end pivotally mounted on the stationary support. Also included is an elevation means coupled to the articulated support at an upper joint and to the stationary support at a lower joint for articulating the articulated support. The upper joint is further from the proximal end than the lower joint. The carrier also has a cargo support mounted for longitudinal motion on the articulated support. The cargo support is operable to detach and reattach to the articulated support at a handoff location located at the proximal end of the articulated support. The carrier also has a motive means for moving the cargo support.
By employing apparatus of the foregoing type, an improved cargo carrier is achieved. In a preferred embodiment, the cargo can be placed on a cargo support formed as a platform having casters at its four corners. This cargo platform can roll in channels of a preferred articulated support. These channels also have rollers at their back end. The angle of elevation of this articulated support can be altered by a hydraulic cylinder. This hydraulic cylinder connects below to a location that is relatively close to the pivot point of the articulated support (in comparison to the connection point of the cylinder to the articulated support itself). This relative placement of the hydraulic cylinder allows it to collapse into a nearly horizontal position, so that the cargo platform can descend to a position close to the truck bed in order to provide a low center of gravity and better stability. This role to placement also reduces the force and stresses placed on the articulated support.
In this preferred embodiment, the cargo platform can extend from the channels of the articulated support, and detach therefrom as the leading edge of the cargo platform touches the ground. Preferably, the descent is controlled by a winch-driven cable, which cable eventually rides over a sheave to lower the trailing edge of the detached cargo platform to the ground. Detachment of the cargo platform is facilitated by a hand lever located near the sheave. This lever can be used to lift the trailing edge of the cargo platform over the sheave and other parts of the articulated support.
In one highly preferred embodiment, the assembly can be detached from the truck bed using quick-release pins. Support legs can then be deployed to support the back end of the assembly. The assembly can then be partially unloaded from the truck bed before additional support legs on the forward end of the assembly are deployed to then allow complete unloading.